It has been reported by some UK outlets that Blues boss Antonio Conte is interested in bringing the Germany international to Stamford Bridge, with a bid of around £20 million thought to be sufficient, to provide Marcos Alonso with competition at left-back.

But while Koln do not want to lose the defender, Stoger admits that the 26-year-old's future is in his own hands.

"I would not say that any player of any club in the world is not for sale, but we have extended Jonas' contract," Stoger is quoted by the Express. "And I think the player is clear - he knows what he wants. If there is any club Jonas is interested in, then we would talk to them.

"But Jonas didn’t say that he wants to leave the club and go to Chelsea so it doesn’t matter.

“If someone wants to leave the club then we have to talk about it, but not before."